/**
 * Config.h
 * Copyright 2012 zhaigy hontlong@gmail.com
 */

#ifndef SRC_CONFIG_H_
#define SRC_CONFIG_H_

#pragma once

#include <string>
#include <map>
#include <iostream>  // NOLINT
#include <fstream>
#include <sstream>

class Config {
  protected:
    // separator between key and value
    std::string m_Delimiter;
    // separator between value and comments
    std::string m_Comment;
    // extracted keys and values
    std::map<std::string, std::string> m_Contents;

    typedef std::map<std::string, std::string>::iterator mapi;
    typedef std::map<std::string, std::string>::const_iterator mapci;

  public:
    Config(std::string filename, std::string delimiter = "=",
          std::string comment = "#");
    Config();
    // Search for key and read value or optional default value, call as read<T>
    template<class T> T Read(const std::string& in_key) const;
    template<class T> T Read(const std::string& in_key,
          const T& in_value) const;
    template<class T> bool ReadInto(T& out_var,
          const std::string& in_key) const;
    template<class T> bool ReadInto(T& out_var, const std::string& in_key,
          const T& in_value) const;
    bool FileExist(std::string filename);
    void ReadFile(std::string filename, std::string delimiter = "=",
          std::string comment = "#");

    // Check whether key exists in configuration
    bool KeyExists(const std::string& in_key) const;

    // Modify keys and values
    template<class T> void Add(const std::string& in_key, const T& in_value);
    void Remove(const std::string& in_key);

    // Check or change configuration syntax
    std::string GetDelimiter() const {
      return m_Delimiter;
    }
    std::string GetComment() const {
      return m_Comment;
    }
    std::string SetDelimiter(const std::string& in_s) {
      std::string old = m_Delimiter;
      m_Delimiter = in_s;
      return old;
    }

    std::string SetComment(const std::string& in_s) {
      std::string old = m_Comment;
      m_Comment = in_s;
      return old;
    }

    // Write or read configuration
    friend std::ostream& operator<<(std::ostream& os, const Config& cf);
    friend std::istream& operator>>(std::istream& is, Config& cf);

  protected:
    template<class T> static std::string T_as_string(const T& t);
    template<class T> static T string_as_T(const std::string& s);
    static void Trim(std::string& inout_s);

  public:
    struct File_not_found {
      std::string filename;
      File_not_found(const std::string& filename_ = std::string()) :
        filename(filename_) {
        }
    };
    // thrown only by T read(key) variant of read()
    struct Key_not_found {
      std::string key;
      Key_not_found(const std::string& key_ = std::string()) :
        key(key_) {
        }
    };
};

/* static */
template<class T>
std::string Config::T_as_string(const T& t) {
  // Convert from a T to a string
  // Type T must support << operator
  std::ostringstream ost;
  ost << t;
  return ost.str();
}

/* static */
template<class T>
T Config::string_as_T(const std::string& s) {
  // Convert from a string to a T
  // Type T must support >> operator
  T t;
  std::istringstream ist(s);
  ist >> t;
  return t;
}

/* static */
template<>
inline std::string Config::string_as_T<std::string>(const std::string& s) {
  // Convert from a string to a string
  // In other words, do nothing
  return s;
}

/* static */
template<>
inline bool Config::string_as_T<bool>(const std::string& s) {
  // Convert from a string to a bool
  // Interpret "false", "F", "no", "n", "0" as false
  // Interpret "true", "T", "yes", "y", "1", "-1", or anything else as true
  bool b = true;
  std::string sup = s;
  for (std::string::iterator p = sup.begin(); p != sup.end(); ++p)
  *p = toupper(*p);  // make string all caps
  if (sup == std::string("FALSE") || sup == std::string("F") || sup
        == std::string("NO") || sup == std::string("N") || sup
        == std::string("0") || sup == std::string("NONE"))
  b = false;
  return b;
}

template<class T>
T Config::Read(const std::string& key) const {
  // Read the value corresponding to key
  mapci p = m_Contents.find(key);
  if (p == m_Contents.end())
  throw Key_not_found(key);
  return string_as_T<T> (p->second);
}

template<class T>
T Config::Read(const std::string& key, const T& value) const {
  // Return the value corresponding to key or given default value
  // if key is not found
  mapci p = m_Contents.find(key);
  if (p == m_Contents.end()) return value;
  return string_as_T<T> (p->second);
}

template<class T>
bool Config::ReadInto(T& var, const std::string& key) const {
  // Get the value corresponding to key and store in var
  // Return true if key is found
  // Otherwise leave var untouched
  mapci p = m_Contents.find(key);
  bool found = (p != m_Contents.end());
  if (found) var = string_as_T<T> (p->second);
  return found;
}

template<class T>
bool Config::ReadInto(T& var, const std::string& key, const T& value) const {
  // Get the value corresponding to key and store in var
  // Return true if key is found
  // Otherwise set var to given default
  mapci p = m_Contents.find(key);
  bool found = (p != m_Contents.end());
  if (found) {
    var = string_as_T<T> (p->second);
  } else {
    var = value;
  }
  return found;
}

template<class T>
void Config::Add(const std::string& in_key, const T& value) {
  // Add a key with given value
  std::string v = T_as_string(value);
  std::string key = in_key;
  Config::Trim(key);
  Config::Trim(v);
  m_Contents[key] = v;
  return;
}
#endif  // SRC_CONFIG_H_

